Specs & Selection — Safety Light Curtains
Choose with engineering discipline: match resolution (beam spacing) to the body part you must protect, ensure protective height covers the hazard aperture, and verify the required sensing distance and response time still satisfy ISO 13855. No fluff—just numbers that hold up in audits.
1) Selection principles & constraints
Control variables
- Resolution (beam spacing, “光轴间距”): 10/14/20/30/40/80/200 mm typical.
- Protective height: 150–1700 mm (choose to cover opening).
- Sensing distance (range): near/far limits; narrow-pitch reduces max range.
- Response time: curtain tr + downstream stop time ts.
- Sync method: wired vs optical (JER). Optical saves cable, wired resists harsh EMI.
Non-negotiables
- Risk requires Type 4, PLe/SIL3 for finger/hand protection.
- Safety distance per ISO 13855: S = K×T + C (see calculator).
- Dual-channel OSSD with EDM feedback; restart on rising-edge only.
- Shielding/routing: keep signal ≥200 mm from VFD bundles; cross at 90°.
2) Selection matrix — spec trade-offs
| Use case | Resolution | Typical protective height | Usable range | Typical response | Why it’s chosen | Watch-outs |
|---|---|---|---|---|---|---|
| Finger protection at tooling (press/brake/robot cell openings) | 10 mm | 500 or 600 mm | 0.3–3 m | ≤ 10–15 ms (curtain only) | Stops a 12–20 mm rod; allows tight safety distances after ISO 13855 calc | Shorter max range; more sensitive to alignment and reflective parts |
| General hand protection, conveyors/packaging, press loading zones | 30/40 mm | 600–1200 mm | 3–6 m | ≤ 12–18 ms | Wide working distance with robust alignment margin | Not for finger-level risks; safety distance increases |
| Tight retrofits inside guards/frames | 10–30 mm on 30×17.5 mm profile | 150–900 mm | 0.3–2.5 m (model-dependent) | ≤ 12–18 ms | Fits legacy holes, minimizes fixture changes | Lower mechanical stiffness; ensure bracket rigidity |
Values are typical for DAIDISIKE DQC/JER families; confirm exact model datasheet before approval.
3) 10 mm finger protection — 500/600 mm height, 0.3–3 m range
When to use Fingers can access the point of operation; you need the smallest feasible safety distance and the acceptance test uses a 14 mm or 20 mm rod depending on the standard.
Mounting: leave 5–10 mm margin from frame edges; avoid mirror finishes within 300 mm; keep windows clean.
| Spec | Recommended | Notes |
|---|---|---|
| Protective height | 500 or 600 mm | Covers typical 450–520 mm openings near dies; stack modules if taller |
| Range | 0.3–3 m | Narrow pitch reduces optical budget; use shrouds near welding arcs |
| Response (curtain) | ≤ 10–15 ms | Add machine stop time before ISO 13855 calculation |
Acceptance: run quarterly test with the proper rod; verify EDM blocks reset on K1/K2 fault.
4) 30/40 mm hand protection — 3–6 m range
When to use Hands can reach but finger-level risk is mitigated by distance/guards; longer distance and more forgiving alignment are required.
| Spec | Recommended | Notes |
|---|---|---|
| Resolution | 30 mm (most common) or 40 mm | Choose 30 mm for smaller parts or closer mounting; 40 mm for extra range |
| Protective height | 600–1200 mm | Set to block the full opening; combine with side guards if needed |
| Range | 3–6 m | Plenty for conveyor edges and robot cells |
5) Slim 30×17.5 mm retrofits — for tight spaces
When a legacy machine has limited envelope or you must reuse brackets, the DQZ/DQC slim bodies drop into 30×17.5 mm slots with minimal tooling changes.
- Profile stiffness is lower than 30×30 mm; use two brackets per bar and add an L-brace on spans > 700 mm.
- Respect range limits (often 0.3–2.5 m for 10–20 mm resolutions).
- Prefer wired sync in heavy-EMI bays; optical sync where cable paths are constrained.
6) 6-step selection workflow + worked example
- Define body part: finger (10–14 mm) vs hand (30/40 mm).
- Measure opening: choose protective height ≥ opening, round up to nearest model.
- Estimate range: install distance + tolerance; check model optical budget.
- Compute distance: ISO 13855 S = K×(t_r + t_s) + C using measured stop-time t_s.
- Choose sync: wired for EMI robustness, optical for cable savings.
- Plan validation: test-rod sweep, EDM reset check, record templates.
Need finger protection at 520 mm opening. Choose DQC-10, 600 mm height. Mount at 450 mm from hazard. Curtain response 12 ms, machine stop-time measured 110 ms → T = 0.122 s. With K = 1600 mm/s and C = 0 mm (front approach), S = 195 mm. Mounting at 450 mm > S → compliant. Document the numbers and attach the stop-time screenshot.
7) FAQ
Is 14 mm “finger protection” better than 10 mm?
Not necessarily. 10 mm captures smaller objects but reduces range and tightens alignment. Choose the smallest resolution needed by the risk assessment and process parts, then verify ISO 13855 distance.
When should I pick optical sync (JER) instead of wired sync (DQC)?
Use optical sync when cable routing is costly or impossible (long spans, moving guards). In severe EMI (welding bays, large VFD clusters), wired sync is usually the safer choice.
How much protective height is “enough”?
It must block the entire hazardous aperture throughout the motion. If the opening varies, size for the worst case or add fixed guards. Stacking is allowed if blanking gaps are within the standard’s limits.